WIP: Node role RPC call (#3719)

* Add a Node Role RPC call

* Formatting

* Fix tests

* Change tests to use NodeRole::Authority so I don't forget to update the test

* Improve role checking

* return a vec instead

* fix tests

substrate/core/rpc/api/src/system/helpers.rs

@@ -50,6 +50,14 @@ pub struct Health {
 	pub should_have_peers: bool,
 }
 
+impl fmt::Display for Health {
+	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+		write!(fmt, "{} peers ({})", self.peers, if self.is_syncing {
+			"syncing"
+		} else { "idle" })
+	}
+}
+
 /// Network Peer information
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
@@ -66,12 +74,17 @@ pub struct PeerInfo<Hash, Number> {
 	pub best_number: Number,
 }
 
-impl fmt::Display for Health {
-	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-		write!(fmt, "{} peers ({})", self.peers, if self.is_syncing {
-			"syncing"
-		} else { "idle" })
-	}
+/// The role the node is running as
+#[derive(Debug, PartialEq, Serialize, Deserialize)]
+pub enum NodeRole {
+	/// The node is a full node
+	Full,
+	/// The node is a light client
+	LightClient,
+	/// The node is an authority
+	Authority,
+	/// An unknown role with a bit number
+	UnknownRole(u8)
 }
 
 #[cfg(test)]

substrate/core/rpc/api/src/system/mod.rs

@@ -24,7 +24,7 @@ use jsonrpc_derive::rpc;
 
 use self::error::Result;
 
-pub use self::helpers::{Properties, SystemInfo, Health, PeerInfo};
+pub use self::helpers::{Properties, SystemInfo, Health, PeerInfo, NodeRole};
 pub use self::gen_client::Client as SystemClient;
 
 /// Substrate system RPC API
@@ -64,4 +64,8 @@ pub trait SystemApi<Hash, Number> {
 	// TODO: make this stable and move structs https://github.com/paritytech/substrate/issues/1890
 	#[rpc(name = "system_networkState", returns = "jsonrpc_core::Value")]
 	fn system_network_state(&self) -> Receiver<jsonrpc_core::Value>;
+
+	/// Returns the roles the node is running as.
+	#[rpc(name = "system_nodeRoles", returns = "Vec<NodeRole>")]
+	fn system_node_roles(&self) -> Receiver<Vec<NodeRole>>;
 }